I'm not against an all-female cast, I'm not against a new cast period. The problem with Ghostbusters, whether they reboot it or continue, is that it will never be Ghostbusters or be accepted as such until the remaining 3 co-sign both on and off screen. Their approval is needed to pass on the torch.
Worst case, have them be a new chapter of Ghostbusters that sprouted in a different city, militia style. And NO Ecto-1. It also has to be able to poke fun at itself. The Ghostbusters were the most disrespected heroes, even with proof.